Spectator not bad idea.
But having someone that could help from outside the group I don't think they would allow it.
Even if no in-game chat for the spectator, have someone on voice that could call for phases, warn people etc...not game breaking but clearly an advantage.

I am not against it, just I don't think they will do it.

As for learning/god mode, the fear itself should be enough (yeah hydra pun intended ) Try and retry is the learning process.

If there was the death penalties from ancient mmos, I would say why not.